igb: Fix Null-pointer dereference in igb_reset_q_vector

When igb_set_interrupt_capability() calls
igb_reset_interrupt_capability() (e.g., because CONFIG_PCI_MSI is unset),
num_q_vectors has been set but no vector has yet been allocated.

igb_reset_interrupt_capability() will then call igb_reset_q_vector,
which assumes that the vector is allocated. As this is not the case, we
are accessing a NULL-pointer.

This patch fixes it by checking that q_vector is indeed different from
NULL.

Fixes: 02ef6e1d0b0023 (igb: Fix queue allocation method to accommodate changing during runtime)
Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index e8b4f7b..6acf787 100644 (file)
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -1035,6 +1035,12 @@ static void igb_reset_q_vector(struct igb_adapter *adapter, int v_idx)
 {
        struct igb_q_vector *q_vector = adapter->q_vector[v_idx];
 
+       /* Coming from igb_set_interrupt_capability, the vectors are not yet
+        * allocated. So, q_vector is NULL so we should stop here.
+        */
+       if (!q_vector)
+               return;
+
        if (q_vector->tx.ring)
                adapter->tx_ring[q_vector->tx.ring->queue_index] = NULL;